This invention relates generally to union-type quick couplings and more particularly to couplings for high-pressure oil and gas pipe and tubes. The invention is directed to both method and apparatus for providing seal redundancy and insuring the integrity of seals used with such couplings.
Union-type couplings are generally used to connect joints of pipe used in temporary test operations conducted at a well site. The union, or quick, couplings provide a faster method for repetitiously making up and breaking down the various pipe and tube configurations used for well testing, completion, and work-over operations.
It is required that prior to pressurizing such well head configurations with well pressure, the test configuration must be pressure tested to the expected well pressure to insure joint seal integrity. This pressure test procedure becomes quite burdensome and time consuming when only one joint is disassembled repeatedly during the test procedure as a result of having to retest the entire string of pipe joints. It would, therefore, be advantageous to have the ability to pressure test the seals in any given coupling in the string, requiring only a fraction of the time.
The instant invention provides a quick coupling union for oil and gas tubular members that provide a more stable joint connection, a redundant seal arrangement, and a method for pressure testing the seals. The union and sealing arrangement includes an elongated tubular receiving member, further including a central longitudinal cavity therein for receiving an elongated tubular insertion member and an external port in communication with the cavity, at least two sealing members located within the cavity defined by the insertion and receiving members and the dual seals being capable of providing a positive seal between the insertion member and the receiving member. The union further includes a nut slidable upon the insertion member for threadably locking the insertion member relative to the receiving member, the sealing members being spaced apart in a manner whereby the external port is interposed between the dual sealing members when the union is fully engaged, thus defining a means for applying a pressure there upon at least equal to the rated pressure of the union and or the anticipated applied pressure rating of the tubular members being attached by the union coupling.